PURPOSE: To acquire high fusion bonding strength by inserting a core section into the end portion of a thermal plastic resin pipe, forming the outer surface side of the core section out of a thermal plastic synthetic resin layer which is fused by induction heating, and thereby producing contact pressure on its fusion boding surface by means of the thermal contraction properties of the thermal plastic resin pipe.

CONSTITUTION: A core section 1 which is inserted into the end portion of a contacted thermal plastic resin pipe, and has a flange section 2 the outer diameter of which is roughly equal to that of a pipe to be connected at its center section, is so formed that its outer diameter is equal to or smaller than the inner diameter of the pipe to be connected. The outer surface side of the core section 1 is provided with a thermal plastic synthetic resin layer 11 which is fused by induction heating. And an induction heating component, for example, a cylindrical mesh 12 composed of a resistance wire, is embedded in the thermal plastic synthetic resin layer 11. When a thermal plastic resin pipe is pat in connection, after the end portion of the pipe to be connected is fitted on the core section 1, the induction heating component 12 is heated by means of a high frequency heating device, consequently generation of heat allows the thermal plastic synthetic resin layer to be fusion bonded to the inner surface of a pipe end portion.